The 6.8mm Remington Special Purpose Cartridge is a rimless bottlenecked intermediate rifle cartridge that was developed by Remington Arms in collaboration with members of the U.S. Army Marksmanship Unit and United States Special Operations Command to possibly replace the 5.56 NATO cartridge in short barreled rifles (SBR) and carbines. Based on the .30 Remington cartridge, it is midway between the 5.56×45mm NATO and 7.62×51mm NATO in bore diameter. It uses the same diameter bullet as the .270 Winchester hunting cartridge.

An intermediate cartridge is a rifle/carbine cartridge that has significantly greater power than a pistol cartridge but still has a reduced muzzle energy compared to fully powered cartridges, and therefore is regarded as being "intermediate" between traditional rifle and handgun cartridges.